UPDATED: The showrunner of the “Halo” series at Paramount Plus will exit the show once work on Season 1 is over, Variety has learned exclusively.

Steven Kane and Kyle Killen were both attached as co-showrunners on the series at one time. According to sources, Killen departed the project ahead of the start of production as he felt he was unable to render full-time showrunner duties during the show’s shoot in Budapest. Kane then took over as the lead showrunner.

Production is currently ongoing on Season 1 of the series, with Kane set to remain onboard through the post-production process. Should the show get picked up for a second season, however, he will not return. Kane has been in Budapest now for the past two years and wishes to return stateside for personal reasons.

A second season pickup seems likely for the series, given the high-profile nature of the underlying IP and the high level of investment on ViacomCBS’ part.

Killen was first announced as being attached to the show when it was originally ordered at Showtime in June 2018. Kane came onboard to co-develop and co-showrun in March 2019.

A live-action adaptation of “Halo” has been in the works for years. Based on the juggernaut video game franchise of the same name, the series will follow “an epic 26th-century conflict between humanity and an alien threat known as the Covenant.” Production had originally begun on the nine-episode first season in late 2019 before it was forced to shutdown due to the COVID-19 pandemic. It was announced that the show would move from Showtime to Paramount Plus in February 2021.

Pablo Schreiber will star as Master Chief Petty Officer John-117, the iconic main character in the games and a super soldier created as part of the Spartan–II program. Natascha McElhone will play Dr. Catherine Halsey, the creator of the Spartan soldiers. Jen Taylor will reprise her role from the games as Cortana, the most advanced AI in human history. Bokeem Woodbine, Shabana Azmi, Bentley Kalu, Natasha Culzac, Kate Kennedy, Danny Sapani, Olive Gray, and Charlie Murphy will also star.

The “Halo” series is being produced by Showtime with 343 Industries, the video game developer behind the first-person shooter franchise. Amblin Television will also produce, with Steven Spielberg, Darryl Frank and Justin Falvey as executive producers. Otto Bathurst and Toby Leslie will executive produce for One Big Picture, with Bathurst also directing multiple episodes. Killen and Scott Pennington executive produce for Chapter Eleven, with Kane also executive producing. Kiki Wolfkill, Frank O’Connor and Bonnie Ross serve as executive producers on behalf of 343 Industries.